Sultan of Sprint: Buell-Powered Hooligan Sportster!

Buell Harley Hooligan

“Good Riddance” — an XB12-powered Sultans of Sprint racer…

The Harley-Davidson Sportster, which has been in continuous production since 1957, remains one of our favorite platforms for customization, readily lending itself to street/dirt tracker builds. That said, the beloved “Sporty” has never been quite as sporty as the name suggests…unless you shoehorn a Buell 1203 Thunderstorm engine into the frame, that is.

Buell Harley Hooligan

That was the inspired idea of Mirko and Nena Nicic, the husband/wife duo behind Croatia’s Rivertown Custom Cycles. Mirko is a former FMX rider, while Nena is a former world championship MX rider. Says Mirko:

“We have, together with family, over 50 years of motocross racing behind us, so it is no wonder that our bikes tend to look like dirt bikes/scramblers/trackers.”

Buell Harley Hooligan

Today, Nena races in Sultans Of Sprint, the European drag racing series that pits vintage-style custom bikes head-to-head on strips, closed roads, and circuit straightaways around Europe:

“All the bikes are vintage style bikes custom built by the best workshops and petrolheads with speed and acceleration in mind.”

Buell Harley Hooligan

For Nena’s sprint racer, they decided to create a hooligan tracker built for drag racing, shoehorning the 100-hp, high-compression V-twin from a 2004 Buell XB12 into the frame of a 1987 Sportster, complete with a giant FCR41 MX carb. Not surprisingly, retrofitting the Buell engine into the Sportster frame was a time-intensive, laborious process:

“In order to put all these parts together, we had to put a lot of hours into measuring, lathing and milling.”

Buell Harley Hooligan

However, the end result was well worth the effort. Nicknamed “Good Riddance,” this Buell-powered Hooligan Sportster is now making its way around Europe, racing in the Sultans of Sprint series and flat track events such as Germany’s Krowdrace.

Below, we get the full story on the Buell/Harley beast, along with photos from the Cafe Racer Festival outside Paris and the Reunion at Monza — the latter courtesy of @vd__photo.

Buell/Harley Hooligan: Builder Interview

Buell Harley Hooligan

• Please tell us a bit about yourself, your history with motorcycles, and your workshop.

Rivertown Custom Cycles is a small custom bike workshop in Croatia on the beautiful island of Rab, where we (my wife Nena and myself) build our bikes and race them. My name is Mirko Nicic and I am a former FMX rider, now still active in MX riding. Nena is former world championship MX rider and now racing in Sultans Of Sprint series in Europe with our Sportster/Buell “Good Riddance”. We have together with family over 50 years of motocross racing behind us, so it is no wonder that our bikes tend to look like dirt bikes/scramblers/trackers.

Buell Harley Hooligan

• What’s the make, model, and year of the bike?

The frame is an ’87 H-D Sportster and the engine came off a 2004 Buell XB12.

Buell Harley Hooligan

• Why was this bike built?

This bike was built for this year’s Sultans Of Sprint sprint races, and also as our wish to build a hooligan bike with a powerful engine that would be able to compete in ¼ mile sprint races.

Buell Harley Hooligan

• What was the design concept and what influenced the build?

The bike is 100% hooligan dirt tracker, with a mean engine, hugely influenced by our love for MX and dirt track racing.

Buell Harley Hooligan

• What custom work was done to the bike?

The building of the bike itself was just enormous amount of measuring, cutting the frame to fit the big XB12 engine (rear cylinder wouldn’t fit) and also trimming the crankcase to fit the frame.

Buell Harley Hooligan

The forks came off a Suzuki GSX-R1000 K3, the tank is from a 1938 NSU Quick, the front wheel is H-D Softail Rocker, and in the rear is the front H-D Sportster wheel.

Buell Harley Hooligan

Braking power is supplied from Free Spirits Parts from Italy — they make 320mm and 300mm braking discs for H-D hubs, which fit perfectly the Tokico brake calipers from the GSX-R. The bike features also big Keihin FCR41 MX carb with custom-made manifold and custom-made exhaust pipes. We used Mitas flattrack tyres that work perfect for the sprint races too!

Buell Harley Hooligan

In order to put all these parts together, we had to put a lot of hours into measuring, lathing and milling.

• Does the bike have a nickname?

This bike has a nickname: Good Riddance.

Buell Harley Hooligan

• How would you classify this bike?

This is hooligan dirt-tracker.

Buell Harley Hooligan

• Was there anything done during this build that you are particularly proud of?

We are very proud of the precise lining up of the engine in the frame (which normally doesn’t fit at all), and also of the perfect performing on the track, both sprint and dirt track.

Buell Harley Hooligan

Photo Credits

Visually Different Photography
Götz Göppert Photography

Follow the Builder

IG: @rivertowncustomcycles
FB: @rivertowncustomcycles




  1. Great bike, love the NSU tank! It would’ve been much easier to fit that engine into a ’91 or newer frame, but I’m sure sportsters don’t exactly grow on trees in Croatia.

  2. Best Hooligan build I’ve seen yet. I would ride that hung everyday. What a beast. Congrats Rivertown! Killing it in Croat!

  3. Ted LeCraw

    That is a Harley I would ride

  4. Very cool combo! Over here, they often put those buell engines in a hardtail chopper kit. I’m leaving mine in my Ulysses, even though I need to get it running again, ugggh.

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